A broadband wireless communication system supports the mobility of a mobile station (MS) through a handover. The MS must know information about neighbor base stations (hereinafter referred to as neighbor BS information) in order to perform a handover. Thus, a serving BS transmits neighbor BS information to the MS. For example, the serving BS collects neighbor BS information through a backbone. Thereafter, using a broadcast message, the serving BS broadcasts the neighbor BS information to mobile stations located in a coverage area.
Base stations of the broadband wireless communication system can use a plurality of frequency allocations (FAs). In this case, the BS supports the mobility of an MS through an intra-FA handover and an inter-FA handover. The intra-FA handover is a handover of an MS from an in-use FA of a serving BS to one of the frequency allocations of a neighbor BS that is identical to the in-use FA.
In order to support an intra-FA handover and an inter-FA handover, the serving BS must transmit information about all subcells of neighbor base stations to the MS. The subcell is a service area that receives a service through one of the frequency allocations used by a BS.
When a serving BS generates a broadcast message in order to transmit information about all subcells of neighbor base stations to an MS, there is an increase in overhead due to the broadcast message. For example, when M neighbor base stations use one FA in a broadband wireless communication system, the serving BS generates a broadcast message containing information about M base stations. However, when M neighbor base stations use N frequency allocations, the serving BS generates a broadcast message containing information about M×N subcells.
Moreover, because the serving BS transmits the broadcast message at the lowest data rate, the size of the broadcast message further increases, leading to a decrease in the available resources for transmission of downlink data.
The MS detects information about neighbor subcells using the broadcast message received from the serving BS. Thereafter, the MS scans subcells that use FAs different from the FA of the MS. However, if the serving BS broadcasts information about all subcells of neighbor base stations, the MS must scan too many subcells, leading to a service interruption.